People who see the glass as half full rather than half empty may be less likely to die from heart disease or stroke. According to a study in Archives of Internal Medicine, optimists may have this added benefit because they exercise more and can deal with misfortune better than their pessimistic counterparts. The study authors followed 545 men between the ages of 64 and 84 for up to 15 years. The men took surveys to determine how optimistic they were. Those who were classified as optimists in 1985 were 55 percent less likely to die from stroke or heart disease by the year 2000 when compared with men who were not classified as optimists. Heart experts agree that a positive attitude could have a significant effect on health. ( Arch Intern Med, February 27, 2006)

The health stories featured on the local news are not always accurate or in context, according to a study in American Journal of Managed Care. Researchers analyzed a representative sample of newscasts from 122 stations in the top 50 media markets in October 2002. They found that 40 percent of the broadcasts contained at least one health-related story, and health stories received an average of 33 seconds per broadcast. However, researchers say these stories may not be used in the right context. For example, 9 percent of health stories analyzed were about West Nile virus. According to researchers, infectious diseases that have higher fatality rates, such as the flu, should receive more attention. They also said that many of the West Nile stories did not tell viewers how to avoid or treat mosquito bites, which could have helped with prevention. Researchers say that one limitation of the study is that certain newsworthy topics are covered at specific times in the news media, which skews the coverage. ( Am J Manag Care, March 2006)

Getting too much or too little sleep may increase the risk of developing diabetes. Authors of a study published in Diabetes Care followed the long-term sleep habits of more than 1,100 men in middle age and beyond who did not have diabetes in 1987 to 1989. The study ended in 2004. The men who slept six hours or less per night or more than eight hours per night had an increased risk of developing type 2 diabetes when compared with the men who usually slept seven to eight hours. The men who slept more than eight hours had three times the risk, and those who slept less than six hours had two times the risk. This diabetes risk remained the same after adjusting for factors such as age, smoking status, and blood pressure; however, risks were reduced by adjusting for testosterone levels. ( Diabetes Care, March 2006)

Can chronic marijuana use affect your mind? Yes, according to a study in Neurology. Researchers administered cognitive tests, which measured such things as memory, attention, and verbal fluency, to 64 persons in a drug-abuse treatment program. Both long- and short-term marijuana users performed worse on the tests than the nonusers (i.e., participants who hadn't used marijuana in at least two years), with the long-term users performing the worst. In a memory test, participants were asked to remember 15 words; the nonusers were able to recall an average of 12 words, whereas long-term users were able to recall only seven. The researchers say that although the link between marijuana use and mental function is not definite, their findings suggest that long-term, chronic use of marijuana may weaken cognitive abilities. These findings add a new twist to the ongoing debate on the effects of marijuana use. ( Neurology, March 14, 2006)

Reduced pollution seems to reduce mortality, according to a study in American Journal of Respiratory and Critical Care Medicine. The authors analyzed data from earlier studies that linked increased mortality with long-term exposure to PM2.5 (small airborne particles 2.5 microns in diameter or less). The authors also analyzed data for an additional eight years of follow-up in U.S. cities that had declining levels of air pollution. They found that overall mortality rates rose in cities with increased levels of PM2.5, whereas mortality rates declined in those same populations when the PM2.5 levels fell. The authors say that the decline in death was specifically related to cardiovascular and respiratory disease but not to lung cancer, which has a longer latency period. This research suggests that increased mortality in relation to PM2.5 may be reversible to some extent. ( Am J Respir Crit Care Med, March 2006)